Re: [PATCH v2 0/5] kallsyms: Emit symbol for holes in text and fix weak function issue

[Zheng Yejian]

On 2025/1/22 01:48, Steven Rostedt wrote:
> Sorry for the late reply. Forgot about this as I was focused on other end-of-year issues.
>
> On Sat, 14 Dec 2024 16:37:59 +0800
> Zheng Yejian <zhengyejian1@xxxxxxxxxx> wrote:
>
> > The direct cause of this issue is the wrong fentry being founded by ftrace_location(),
> > following the approach of "FTRACE_MCOUNT_MAX_OFFSET", narrowing down the search range
> > and re-finding may also solve this problem, demo patch like below (not
> > fully tested):
> >
> >       diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> >       index 9b17efb1a87d..7d34320ca9d1 100644
> >       --- a/kernel/trace/ftrace.c
> >       +++ b/kernel/trace/ftrace.c
> >       @@ -1678,8 +1678,11 @@ unsigned long ftrace_location(unsigned long ip)
> >                               goto out;
> >       
> >                       /* map sym+0 to __fentry__ */
> >       -               if (!offset)
> >       +               if (!offset) {
> >                               loc = ftrace_location_range(ip, ip + size - 1);
> >       +                       while (loc > ip && loc - ip > FTRACE_MCOUNT_MAX_OFFSET)
> >       +                               loc = ftrace_location_range(ip, loc - 1);
> >       +               }
> >               }
> >
> > Steve, Peter, what do you think?
>
> Hmm, removing the weak functions from the __mcount_loc location should also
> solve this, as the ftrace_location_range() will not return a weak function
> if it's not part of the __mcount_loc table.
>
> That is, would this patchset work?
>
>    https://lore.kernel.org/all/20250102232609.529842248@xxxxxxxxxxx/

I only pick patch15 and patch16 into v6.14-rc1, since most of patches in that patches
have already merged, and the issue seems gone, thanks!

> -- Steve

--
Thanks,
Zheng Yejian